Such type adjustment devices are state of the art. Beside the adjustment device equipped with an electric motor, there are also hand-operated adjustment devices, to which the invention is not directed though. Adjustment devices of the type mentioned herein above are known from U.S. Pat. No. 6,659,548 B1, US 2006/0260424 A1, DE 10 2005 059 693 A1, DE 10 2005 050 971 A1 and DE 10 2005 050 223 A1 for example.
A problem with the prior art adjustment devices is their weight. In particular the electric motor of an adjustment device contributes significantly to the overall weight of the adjustment device. The permanent magnets of an electric motor have a considerable mass and considerably participate in determining the overall weight of the motor. This applies in particular for modern magnet alloys as they are being increasingly used, such as neodymium.
Another problem beside the weight is the volume. Today, modern vehicle seats are equipped with many adjustment devices and place many different demands on the dimensions, the position of the passenger, the seat position often being desired to be as deep as possible and the like, which are to be met, so that it is difficult to accommodate the various adjustment devices within the package space available. Insofar, it is advantageous to provide the possibility of utilizing small adjustment devices as far as practicable. On the prior art adjustment devices, the electric motor as it is presently utilized occupies a considerable volume. It would be advantageous if volume, and space as a result thereof, could be saved.